卡通渲染

CartoonRenderingofSmokeAnimations

AndrewSelle StanfordUniversity

AlexMohrPixar

StephenChenneyUWMadison

Abstract

Wesmoke.describeatechniqueforgeneratingcartoonstyleanimationsoflatorofandOurusesmethodittodrivetakesparticlestheoutputthatofarearenderedphysically-basedusingavariantsimu-trees).thedepthlutionSpeci cdifferencesissuestechnique(originallyusedforrenderingcoherence.ofprimitivesthatTheresultsinwetheaddressincludetheplacementandevo-are owvisuallyandthemaintenanceoftemporaloutlines.

conveytheturbulent,dynamicsimple,natureof icker-freethegaswithanimationssimpleCRCategories:I.3.0[ComputerGraphics]:General

Keywords:ing,non-photorealisticsmokerendering,rendering

smokesimulation,cartoonrender-1Introduction

Consideraryapuffofsmoke.Acartoonistmightdrawaswirlybound-photographwithasolidwhiteinterior,andmaybesomeinternalswirls.Adrivenwebytheofequationssmokere ectscomplexvolumetriclightinteractions,torealisticprefertheabstract,swirlyof uidform,dynamics.whileforForspecialstylizedeffectsanimationsamatedThisresultisdesired.

pho-the uidonesmoke.paperdescribesatechniqueforcartoonrenderingofani-shownOuraimistogeneratestylizedanimationssuchassilhouettes.natureofonthethegasleftusinginFigureonly1,solidwhichblocksconveysofcolortheturbulent,andhardbasedOurmethodisdrivenbytheoutputofaphysically-gaseoussimulator, ow,behavior.ensuringthattheanimated owisconsistentwithinFiguresuchasdensity,WewhichalsohaveweaccesscanusetotophysicalmodifypropertiestherenderingoftheassmokeOurcontribution1.

isamethodforproducinganartistic,torbasic(inrenderingourfromaphysically-basedsimulation.Theanimatedsimula-mass uidcaseFedkiwet.al.’s[2001]algorithm)ensuresthattheatureisconserved,motionisandplausible;thevelocity eldevolvescorrectly,themareofwithconsistent.the ow.TheseWescalarembed eldsparticlessuchasinpressurethe uidandandtemper-advecttechnique.DeussenanddepthParticleStrothotte’sprimitives[2000]arethenrenderedusinganextensionarerendereddepthdifferencesandthentreepixelsrenderinghouettes.differsSeveralsigni cantlyinnovationsfromweretheirrequiredneighborstoadaptaredrawnwhosethebasicassil-al- email:

aselle@cs.stanford.edu

Figuresystem,1:Left:framefroma uidanimationgeneratedbyoursmokebyandinanabstractrenderingstylereminiscentofhand-drawnsensevelocityclouds.ofbillowing,magnitude.Right:anotherframefromoursystem,coloredturbulentOur owstylizedasphotorealisticrenderingscapturesmoke.thesamegorithmprimitivestosmokeanimation,includingamethodforevolvingetc.),mation,shapingtore ectpropertiesofthe ow(densities,temperatures,theandstrategiesandorientingformaintainingparticlesdynamicallytemporalcoherence.

toconveyinfor-1.1RelatedWork

Particlerealsystemsaretypicallyusedtoguidetimetotheapplications,evolutionofbillboardsuchascomputersimulateandrendersmokeinparticlesgames.thatareProceduralrulesusinggivetheappearanceofsmoke.Astylizedlookblendedtogether reAnmodelingnon-photorealisticworkisaverybillboards;highqualityLamorletteexampleandcanofFoster’sbeachievedthisapproach.[2002]texturesalternativeformed[Wittingforstylized1999;Neyretrendering2003],isadvectednon-photorealisticdetailasbythethe ow ow.evolvesThisinwhichatextureisde-andapproach,thetexturehowever,typicallyremovestoOurlargede netargettheshapestyles,andhowever,motionrequireofthe ow,hardmixes.

butedgesininsomeregionscannotlowdetailregions.Blendedbillboardortexturecoexistenceapproacheswithwillsoftproduceeasilyunnecessaryproducethisdetailresult:renderinghard-edgebillboardsdif cultedge owtobillboardsde netextureswouldfailtoinde nethemiddletheedges.oftheItcloud,issimilarlywhiletageevolves.tocapturethiseffectandmaintainitasthemotion,ofrequiringBillboardaparticle-basedparticlesystemshavetheseconddisadvan-hearttionsaparticle-basedwhichisnotalwaysapproach,easyproceduraltoderive.modelWhileofourtheworksmoke’sisatdifferencestoensurealgorithmplausibletothe ow,renderingandweforusephysically-basedsimula-ofthe rsttimeapplyadepthimagesYuet.consistingofal.cartoon[2000]smoke.describeTheyaproceduralsmokede neamodelbillboards.

spineforforthegeneratingstillcreaseswithofheightasinefromcurvethewithsource.frequencyTheirandmodelamplitudesmoke-trailonlyappliesthatin-to